Raspberry leaf blotch virus, a new virus of raspberry
During the last decades, a disorder called leaf blotch has emerged in some raspberry (Rubus idaeus) and tayberry (Rubus hybrids) plantations in England and Scotland (United Kingdom). The disease is affecting in particular the raspberry cultivar ‘Glen Ample’ when grown in protective tunnels. Diseased plants display symptoms of leaf chlorosis, distortion and patchy necrosis combined with a thinning leading to death of lateral branches and subsequent loss of fruit yield. Another clear symptom was a sectoring of the leaf where smooth, apparently hairless patches appeared on the leaf underside. This disease had previously been attributed to the eriophyid raspberry leaf and bud mite (Phyllocoptes gracilis), but recent studies have showed that a new virus, tentatively called Raspberry leaf blotch virus (RLBV), was associated with this disease. Preliminary studies strongly suggest that RLBV is transmitted by P. gracilis. The genome structure and viral protein sequences indicate that RLBV is a new member of the very recently described Emaravirus* genus of plant viruses. Following the identification of the virus, larger scale surveys were undertaken in Scotland, England and Serbia, and the virus was detected in plants exhibiting symptoms of raspberry leaf blotch disease collected from these three countries. Finally, during surveys conducted in Eastern Finland in June 2011, it was observed that raspberry cv. ‘Glen Ample’ grown under plastic tunnels and open fields displayed symptoms of raspberry leaf blotch disease. Leaf samples were collected and laboratory studies confirmed the presence of RLBV in diseased plants.
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* Other members of this new Emaravirus genus include European mountain ash ringspot-associated virus (type species), and probably Fig mosaic virus and Rose rosette virus. All these viruses are transmitted by mites.
Sources
Bi Y, Artola K, Kurokura T, Hytönen T, Valkonen JPT (2012) First report of Raspberry leaf blotch virus in raspberries in Finland. Plant Disease 96(8), p 231.
INTERNET
The James Hutton Institute. Poster by McGavin W, Mitchell C, Cock P, MacFarlane S (undated) Raspberry leaf blotch virus, a new virus isolated from raspberry (Rubus idaeus). http://www.hutton.ac.uk/webfm_send/365
Jones AT, Gordon SC, Jennings DL (1984) A leaf-blotch disorder of tayberry associated with the leaf and bud mite (Phyllocoptes gracilis) and some effects of three aphid-borne viruses. The Journal of Horticultural Science ; Biotechnology 59(4), 523-528 (abst.).
McGavin WJ, Mitchell C, Cock PJA, Wright KM, MacFarlane SA (2011) Raspberry leaf blotch virus, a putative new member of the genus Emaravirus, encodes a novel genomic RNA. Journal of General Virology 93, 430-437.